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Baptista BO, de Souza ABL, Riccio EKP, Bianco-Junior C, Totino PRR, Martins da Silva JH, Theisen M, Singh SK, Amoah LE, Ribeiro-Alves M, Souza RM, Lima-Junior JC, Daniel-Ribeiro CT, Pratt-Riccio LR. Naturally acquired antibody response to a Plasmodium falciparum chimeric vaccine candidate GMZ2.6c and its components (MSP-3, GLURP, and Pfs48/45) in individuals living in Brazilian malaria-endemic areas. Malar J 2022; 21:6. [PMID: 34983540 PMCID: PMC8729018 DOI: 10.1186/s12936-021-04020-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 12/09/2021] [Indexed: 12/19/2022] Open
Abstract
Background The GMZ2.6c malaria vaccine candidate is a multi-stage Plasmodium falciparum chimeric protein which contains a fragment of the sexual-stage Pfs48/45-6C protein genetically fused to GMZ2, a fusion protein of GLURP and MSP-3, that has been shown to be well tolerated, safe and immunogenic in clinical trials performed in a malaria-endemic area of Africa. However, there is no data available on the antigenicity or immunogenicity of GMZ2.6c in humans. Considering that circulating parasites can be genetically distinct in different malaria-endemic areas and that host genetic factors can influence the immune response to vaccine antigens, it is important to verify the antigenicity, immunogenicity and the possibility of associated protection in individuals living in malaria-endemic areas with different epidemiological scenarios. Herein, the profile of antibody response against GMZ2.6c and its components (MSP-3, GLURP and Pfs48/45) in residents of the Brazilian Amazon naturally exposed to malaria, in areas with different levels of transmission, was evaluated. Methods This study was performed using serum samples from 352 individuals from Cruzeiro do Sul and Mâncio Lima, in the state of Acre, and Guajará, in the state of Amazonas. Specific IgG, IgM, IgA and IgE antibodies and IgG subclasses were detected by Enzyme-Linked Immunosorbent Assay. Results The results showed that GMZ2.6c protein was widely recognized by naturally acquired antibodies from individuals of the Brazilian endemic areas with different levels of transmission. The higher prevalence of individuals with antibodies against GMZ2.6c when compared to its individual components may suggest an additive effect of GLURP, MSP-3, and Pfs48/45 when inserted in a same construct. Furthermore, naturally malaria-exposed individuals predominantly had IgG1 and IgG3 cytophilic anti-GMZ2.6c antibodies, an important fact considering that the acquisition of anti-malaria protective immunity results from a delicate balance between cytophilic/non-cytophilic antibodies. Interestingly, anti-GMZ2.6c antibodies seem to increase with exposure to malaria infection and may contribute to parasite immunity. Conclusions The data showed that GMZ2.6c protein is widely recognized by naturally acquired antibodies from individuals living in malaria-endemic areas in Brazil and that these may contribute to parasite immunity. These data highlight the importance of GMZ2.6c as a candidate for an anti-malarial vaccine. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-04020-6.
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Affiliation(s)
- Barbara Oliveira Baptista
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | - Ana Beatriz Lopes de Souza
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | - Evelyn Kety Pratt Riccio
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | - Cesare Bianco-Junior
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | - Paulo Renato Rivas Totino
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | | | - Michael Theisen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Susheel Kumar Singh
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Linda Eva Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Marcelo Ribeiro-Alves
- Laboratório de Pesquisa Clínica em DST e AIDS, Instituto Nacional de Infectologia Evandro Chagas, Fiocruz, Rio de Janeiro, Brazil
| | - Rodrigo Medeiros Souza
- Laboratório de Doenças Infecciosas na Amazônia Ocidental, Universidade Federal do Acre, Acre, Brazil
| | | | - Cláudio Tadeu Daniel-Ribeiro
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil.,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil
| | - Lilian Rose Pratt-Riccio
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil. .,Centro de Pesquisa, Diagnóstico e Treinamento em Malária, Fiocruz, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brazil.
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2
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Muthui MK, Takashima E, Omondi BR, Kinya C, Muasya WI, Nagaoka H, Mwai KW, Orindi B, Wambua J, Bousema T, Drakeley C, Blagborough AM, Marsh K, Bejon P, Kapulu MC. Characterization of Naturally Acquired Immunity to a Panel of Antigens Expressed in Mature P. falciparum Gametocytes. Front Cell Infect Microbiol 2021; 11:774537. [PMID: 34869075 PMCID: PMC8633105 DOI: 10.3389/fcimb.2021.774537] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction Naturally acquired immune responses against antigens expressed on the surface of mature gametocytes develop in individuals living in malaria-endemic areas. Evidence suggests that such anti-gametocyte immunity can block the development of the parasite in the mosquito, thus playing a role in interrupting transmission. A better comprehension of naturally acquired immunity to these gametocyte antigens can aid the development of transmission-blocking vaccines and improve our understanding of the human infectious reservoir. Methods Antigens expressed on the surface of mature gametocytes that had not previously been widely studied for evidence of naturally acquired immunity were identified for protein expression alongside Pfs230-C using either the mammalian HEK293E or the wheat germ cell-free expression systems. Where there was sequence variation in the candidate antigens (3D7 vs a clinical isolate PfKE04), both variants were expressed. ELISA was used to assess antibody responses against these antigens, as well as against crude stage V gametocyte extract (GE) and AMA1 using archived plasma samples from individuals recruited to participate in malaria cohort studies. We analyzed antibody levels (estimated from optical density units using a standardized ELISA) and seroprevalence (defined as antibody levels greater than three standard deviations above the mean levels of a pool of malaria naïve sera). We described the dynamics of antibody responses to these antigens by identifying factors predictive of antibody levels using linear regression models. Results Of the 25 antigens selected, seven antigens were produced successfully as recombinant proteins, with one variant antigen, giving a total of eight proteins for evaluation. Antibodies to the candidate antigens were detectable in the study population (N = 216), with seroprevalence ranging from 37.0% (95% CI: 30.6%, 43.9%) for PSOP1 to 77.8% (95% CI: 71.6%, 83.1%) for G377 (3D7 variant). Responses to AMA1 and GE were more prevalent than those to the gametocyte proteins at 87.9% (95% CI: 82.8%, 91.9%) and 88.3% (95% CI: 83.1%, 92.4%), respectively. Additionally, both antibody levels and breadth of antibody responses were associated with age and concurrent parasitaemia. Conclusion Age and concurrent parasitaemia remain important determinants of naturally acquired immunity to gametocyte antigens. Furthermore, we identify novel candidates for transmission-blocking activity evaluation.
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Affiliation(s)
- Michelle K Muthui
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Brian R Omondi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Christine Kinya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - William I Muasya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Kennedy W Mwai
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Benedict Orindi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Juliana Wambua
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Andrew M Blagborough
- Division of Microbiology and Parasitology, Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, United Kingdom
| | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Melissa C Kapulu
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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3
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Acquah FK, Lo AC, Akyea-Mensah K, Abagna HB, Faye B, Theisen M, Gyan BA, Amoah LE. Stage-specific Plasmodium falciparum immune responses in afebrile adults and children living in the Greater Accra Region of Ghana. Malar J 2020; 19:64. [PMID: 32041620 PMCID: PMC7011432 DOI: 10.1186/s12936-020-3146-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/30/2020] [Indexed: 12/02/2022] Open
Abstract
Background Asymptomatic carriage of Plasmodium falciparum is widespread in adults and children living in malaria-endemic countries. This study identified the prevalence of malaria parasites and the corresponding levels of naturally acquired anti-parasite antibody levels in afebrile adults living in two communities in the Greater Accra Region of Ghana. Methods Two cross-sectional studies conducted in January and February 2016 and repeated in July and August 2016 recruited subjects aged between 6 and 75 years from high parasite prevalence (Obom) and low parasite prevalence (Asutsuare) communities. Whole blood (5 ml) was collected from each volunteer, plasma was aliquoted and frozen until needed. An aliquot (10 µl) of the blood was used to prepare thick and thin blood smears, 100 µl was preserved in Trizol and the rest was separated into plasma and blood cells and each stored at − 20 °C until needed. Anti-MSP3 and Pfs230 antibody levels were measured using ELISA. Results Asexual parasite and gametocyte prevalence were higher in Obom than Asutsuare. Antibody (IgG, IgG1, IgG3, IgM) responses against the asexual parasite antigen MSP3 and gametocyte antigen Pfs230 were higher in Obom during the course of the study except for IgM responses against Pfs230, which was higher in Asutsuare than in Obom during the rainy season. Antibody responses in Asutsuare were more significantly associated with age than the responses measured in Obom. Conclusion The pattern of antibody responses measured in people living in the high and low malaria transmission setting was similar. All antibody responses measured against the asexual antigen MSP3 increased, however, IgG and IgG1 responses against gametocyte antigen Pfs230 decreased in moving from the dry to the peak season in both sites. Whilst asexual and gametocyte prevalence was similar between the seasons in the low transmission setting, in the high transmission setting asexual parasite prevalence increased but gametocyte prevalence decreased in the rainy season relative to the dry season.
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Affiliation(s)
- Festus K Acquah
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana.,West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Aminata C Lo
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana.,Parasitology Department, University Cheikh Anta Diop, Dakar, Senegal
| | - Kwadwo Akyea-Mensah
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana
| | - Hamza B Abagna
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana
| | - Babacar Faye
- Parasitology Department, University Cheikh Anta Diop, Dakar, Senegal
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Ben A Gyan
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana
| | - Linda E Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, Accra, Ghana. .,West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana.
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de Jong RM, Tebeje SK, Meerstein‐Kessel L, Tadesse FG, Jore MM, Stone W, Bousema T. Immunity against sexual stage Plasmodium falciparum and Plasmodium vivax parasites. Immunol Rev 2020; 293:190-215. [PMID: 31840844 PMCID: PMC6973022 DOI: 10.1111/imr.12828] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/14/2019] [Indexed: 12/25/2022]
Abstract
The efficient spread of malaria from infected humans to mosquitoes is a major challenge for malaria elimination initiatives. Gametocytes are the only Plasmodium life stage infectious to mosquitoes. Here, we summarize evidence for naturally acquired anti-gametocyte immunity and the current state of transmission blocking vaccines (TBV). Although gametocytes are intra-erythrocytic when present in infected humans, developing Plasmodium falciparum gametocytes may express proteins on the surface of red blood cells that elicit immune responses in naturally exposed individuals. This immune response may reduce the burden of circulating gametocytes. For both P. falciparum and Plasmodium vivax, there is a solid evidence that antibodies against antigens present on the gametocyte surface, when co-ingested with gametocytes, can influence transmission to mosquitoes. Transmission reducing immunity, reducing the burden of infection in mosquitoes, is a well-acknowledged but poorly quantified phenomenon that forms the basis for the development of TBV. Transmission enhancing immunity, increasing the likelihood or intensity of transmission to mosquitoes, is more speculative in nature but is convincingly demonstrated for P. vivax. With the increased interest in malaria elimination, TBV and monoclonal antibodies have moved to the center stage of malaria vaccine development. Methodologies to prioritize and evaluate products are urgently needed.
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MESH Headings
- Antibodies, Blocking/immunology
- Antibodies, Protozoan/immunology
- Host-Parasite Interactions/immunology
- Humans
- Immunity
- Immunomodulation
- Life Cycle Stages
- Malaria Vaccines/immunology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Malaria, Vivax/immunology
- Malaria, Vivax/parasitology
- Malaria, Vivax/prevention & control
- Malaria, Vivax/transmission
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Plasmodium vivax/growth & development
- Plasmodium vivax/immunology
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Affiliation(s)
- Roos M. de Jong
- Radboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | | | - Lisette Meerstein‐Kessel
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
- Centre for Molecular and Biomolecular InformaticsRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Fitsum G. Tadesse
- Armauer Hansen Research InstituteAddis AbabaEthiopia
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Matthijs M. Jore
- Radboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Will Stone
- Department of Immunology and InfectionLondon School of Hygiene and Tropical MedicineLondonUK
| | - Teun Bousema
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
- Department of Immunology and InfectionLondon School of Hygiene and Tropical MedicineLondonUK
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Structural delineation of potent transmission-blocking epitope I on malaria antigen Pfs48/45. Nat Commun 2018; 9:4458. [PMID: 30367064 PMCID: PMC6203815 DOI: 10.1038/s41467-018-06742-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/17/2018] [Indexed: 12/28/2022] Open
Abstract
Interventions that can block the transmission of malaria-causing Plasmodium falciparum (Pf) between the human host and Anopheles vector have the potential to reduce the incidence of malaria. Pfs48/45 is a gametocyte surface protein critical for parasite development and transmission, and its targeting by monoclonal antibody (mAb) 85RF45.1 leads to the potent reduction of parasite transmission. Here, we reveal how the Pfs48/45 6C domain adopts a (SAG1)-related-sequence (SRS) fold. We structurally delineate potent epitope I and show how mAb 85RF45.1 recognizes an electronegative surface with nanomolar affinity. Analysis of Pfs48/45 sequences reveals that polymorphisms are rare for residues involved at the binding interface. Humanization of rat-derived mAb 85RF45.1 conserved the mode of recognition and activity of the parental antibody, while also improving its thermostability. Our work has implications for the development of transmission-blocking interventions, both through improving vaccine designs and the testing of passive delivery of mAbs in humans. Malaria protein Pfs48/45 is a promising transmission-blocking antigen targeted by antibodies. Here, the authors determine the structure of its transmission-blocking epitope I, and generate a humanized monoclonal antibody that binds Pfs48/45 with high affinity.
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6
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Sinden RE. Antimalarial transmission-blocking vaccines. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2016. [DOI: 10.1080/00034983.1997.11813242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Vallejo AF, Martinez NL, Tobon A, Alger J, Lacerda MV, Kajava AV, Arévalo-Herrera M, Herrera S. Global genetic diversity of the Plasmodium vivax transmission-blocking vaccine candidate Pvs48/45. Malar J 2016; 15:202. [PMID: 27067024 PMCID: PMC4828788 DOI: 10.1186/s12936-016-1263-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 03/31/2016] [Indexed: 12/17/2022] Open
Abstract
Background Plasmodium vivax 48/45 protein is expressed on the surface of gametocytes/gametes and plays a key role in gamete fusion during fertilization. This protein was recently expressed in Escherichia coli host as a recombinant product that was highly immunogenic in mice and monkeys and induced antibodies with high transmission-blocking activity, suggesting its potential as a P. vivax transmission-blocking vaccine candidate. To determine sequence polymorphism of natural parasite isolates and its potential influence on the protein structure, all pvs48/45 sequences reported in databases from around the world as well as those from low-transmission settings of Latin America were compared. Methods Plasmodium vivax parasite isolates from malaria-endemic regions of Colombia, Brazil and Honduras (n = 60) were used to sequence the Pvs48/45 gene, and compared to those previously reported to GenBank and PlasmoDB (n = 222). Pvs48/45 gene haplotypes were analysed to determine the functional significance of genetic variation in protein structure and vaccine potential. Results Nine non-synonymous substitutions (E35K, Y196H, H211N, K250N, D335Y, E353Q, A376T, K390T, K418R) and three synonymous substitutions (I73, T149, C156) that define seven different haplotypes were found among the 282 isolates from nine countries when compared with the Sal I reference sequence. Nucleotide diversity (π) was 0.00173 for worldwide samples (range 0.00033–0.00216), resulting in relatively high diversity in Myanmar and Colombia, and low diversity in Mexico, Peru and South Korea. The two most frequent substitutions (E353Q: 41.9 %, K250N: 39.5 %) were predicted to be located in antigenic regions without affecting putative B cell epitopes or the tertiary protein structure. Conclusions There is limited sequence polymorphism in pvs48/45 with noted geographical clustering among Asian and American isolates. The low genetic diversity of the protein does not influence the predicted antigenicity or protein structure and, therefore, supports its further development as transmission-blocking vaccine candidate.
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Affiliation(s)
| | | | | | - Jackeline Alger
- Facultad de Ciencias Médicas, Hospital Escuela Universitario, Universidad Nacional Autónoma de Honduras, Tegucigalpa, Honduras
| | - Marcus V Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Andrey V Kajava
- Centre de Recherches Biochimie Macromoléculaire (CRBM), Institut de Biologie Computationnelle (IBC), CNRS, University of Montpellier, Montpellier, France.,Institute of Bioengineering, University ITMO, Saint Petersburg, Russia
| | - Myriam Arévalo-Herrera
- Caucaseco Scientific Research Center, Cali, Colombia.,School of Health, Universidad del Valle, Cali, Colombia
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Abstract
Gametocytes are the specialized form of Plasmodium parasites that are responsible for human-to-mosquito transmission of malaria. Transmission of gametocytes is highly effective, but represents a biomass bottleneck for the parasite that has stimulated interest in strategies targeting the transmission stages separately from those responsible for clinical disease. Studying targets of naturally acquired immunity against transmission-stage parasites may reveal opportunities for novel transmission reducing interventions, particularly the development of a transmission blocking vaccine (TBV). In this review, we summarize the current knowledge on immunity against the transmission stages of Plasmodium. This includes immune responses against epitopes on the gametocyte-infected erythrocyte surface during gametocyte development, as well as epitopes present upon gametocyte activation in the mosquito midgut. We present an analysis of historical data on transmission reducing immunity (TRI), as analysed in mosquito feeding assays, and its correlation with natural recognition of sexual stage specific proteins Pfs48/45 and Pfs230. Although high antibody titres towards either one of these proteins is associated with TRI, the presence of additional, novel targets is anticipated. In conclusion, the identification of novel gametocyte-specific targets of naturally acquired immunity against different gametocyte stages could aid in the development of potential TBV targets and ultimately an effective transmission blocking approach.
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Wu Y, Sinden RE, Churcher TS, Tsuboi T, Yusibov V. Development of malaria transmission-blocking vaccines: from concept to product. ADVANCES IN PARASITOLOGY 2015; 89:109-52. [PMID: 26003037 DOI: 10.1016/bs.apar.2015.04.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Despite decades of effort battling against malaria, the disease is still a major cause of morbidity and mortality. Transmission-blocking vaccines (TBVs) that target sexual stage parasite development could be an integral part of measures for malaria elimination. In the 1950s, Huff et al. first demonstrated the induction of transmission-blocking immunity in chickens by repeated immunizations with Plasmodium gallinaceum-infected red blood cells. Since then, significant progress has been made in identification of parasite antigens responsible for transmission-blocking activity. Recombinant technologies accelerated evaluation of these antigens as vaccine candidates, and it is possible to induce effective transmission-blocking immunity in humans both by natural infection and now by immunization with recombinant vaccines. This chapter reviews the efforts to produce TBVs, summarizes the current status and advances and discusses the remaining challenges and approaches.
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Affiliation(s)
- Yimin Wu
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
| | | | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Takafumi Tsuboi
- Division of Malaria Research, Ehime University, Matsuyama, Ehime, Japan
| | - Vidadi Yusibov
- Fraunhofer USA Center for Molecular Biotechnology, Newark, DE, USA
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10
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Tachibana M, Suwanabun N, Kaneko O, Iriko H, Otsuki H, Sattabongkot J, Kaneko A, Herrera S, Torii M, Tsuboi T. Plasmodium vivax gametocyte proteins, Pvs48/45 and Pvs47, induce transmission-reducing antibodies by DNA immunization. Vaccine 2015; 33:1901-8. [PMID: 25765968 DOI: 10.1016/j.vaccine.2015.03.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 02/13/2015] [Accepted: 03/02/2015] [Indexed: 11/18/2022]
Abstract
Malaria transmission-blocking vaccines (TBV) aim to interfere with the development of the malaria parasite in the mosquito vector, and thus prevent spread of transmission in a community. To date three TBV candidates have been identified in Plasmodium vivax; namely, the gametocyte/gamete protein Pvs230, and the ookinete surface proteins Pvs25 and Pvs28. The Plasmodium falciparum gametocyte/gamete stage proteins Pfs48/45 and Pfs47 have been studied as TBV candidates, and Pfs48/45 shown to induce transmission-blocking antibodies, but the candidacy of their orthologs in P. vivax, Pvs48/45 (PVX_083235) and Pvs47 (PVX_083240), for vivax TBV have not been tested. Herein we investigated whether targeting Pvs48/45 and Pvs47 can inhibit parasite transmission to mosquitoes, using P. vivax isolates obtained in Thailand. Mouse antisera directed against the products from plasmids expressing Pvs48/45 and Pvs47 detected proteins of approximately 45- and 40-kDa, respectively, in the P. vivax gametocyte lysate, by Western blot analysis under non-reducing conditions. In immunofluorescence assays Pvs48/45 was detected predominantly on the surface and Pvs47 was detected in the cytoplasm of gametocytes. Membrane feeding transmission assays demonstrated that anti-Pvs48/45 and -Pvs47 mouse sera significantly reduced the number of P. vivax oocysts developing in the mosquito midgut. Limited amino acid polymorphism of these proteins was observed among 27 P. vivax isolates obtained from Thailand, Vanuatu, and Colombia; suggesting that polymorphism may not be an impediment for the utilization of Pvs48/45 and Pvs47 as TBV antigens. In one Thai isolate we found that the fourth cysteine residue in the Pvs47 cysteine-rich domain (CRD) III (amino acid position 337) is substituted to phenylalanine. However, antibodies targeting Pvs47 CRDI-III showed a significant transmission-reducing activity against this isolate, suggesting that this substitution in Pvs47 was not critical for recognition by the generated antibodies. In conclusion, our results indicate that Pvs48/45 and Pvs47 are potential transmission-blocking vaccine candidates of P. vivax.
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Affiliation(s)
- Mayumi Tachibana
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Nantavadee Suwanabun
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Hideyuki Iriko
- Department of Parasitology, Faculty of Health Sciences, Kobe University Graduate School of Health Sciences, Kobe 654-0142, Japan
| | - Hitoshi Otsuki
- Division of Medical Zoology, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8503, Japan
| | - Jetsumon Sattabongkot
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand
| | - Akira Kaneko
- Department of Parasitology, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan; Island Malaria Group, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Socrates Herrera
- Malaria Vaccine and Drug Development Center, Cali AA 25574, Colombia
| | - Motomi Torii
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan.
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
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11
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Turner L, Wang CW, Lavstsen T, Mwakalinga SB, Sauerwein RW, Hermsen CC, Theander TG. Antibodies against PfEMP1, RIFIN, MSP3 and GLURP are acquired during controlled Plasmodium falciparum malaria infections in naïve volunteers. PLoS One 2011; 6:e29025. [PMID: 22174947 PMCID: PMC3236238 DOI: 10.1371/journal.pone.0029025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 11/18/2011] [Indexed: 11/19/2022] Open
Abstract
Antibodies to polymorphic antigens expressed during the parasites erythrocytic stages are important mediators of protective immunity against P. falciparum malaria. Therefore, polymorphic blood stage antigens like MSP3, EBA-175 and GLURP and variant surface antigens PfEMP1 and RIFIN are considered vaccine candidates. However, to what extent these antibodies to blood stage antigens are acquired during naive individuals' first infections has not been studied in depth. Using plasma samples collected from controlled experimental P. falciparum infections we show that antibodies against variant surface antigens, PfEMP1 and RIFIN as well as MSP3 and GLURP, are acquired during a single short low density P. falciparum infection in non-immune individuals including strain transcendent PfEMP1 immune responses. These data indicate that the immunogenicity of the variant surface antigens is similar to the less diverse merozoite antigens. The acquisition of a broad and strain transcendent repertoire of PfEMP1 antibodies may reflect a parasite strategy of expressing most or all PfEMP1 variants at liver release optimizing the likelihood of survival and establishment of chronic infections in the new host.
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Affiliation(s)
- Louise Turner
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Christian W. Wang
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Steven B. Mwakalinga
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Robert W. Sauerwein
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Cornelus C. Hermsen
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Thor G. Theander
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
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12
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Naturally acquired immune responses to Plasmodium falciparum sexual stage antigens Pfs48/45 and Pfs230 in an area of seasonal transmission. Infect Immun 2011; 79:4957-64. [PMID: 21969000 DOI: 10.1128/iai.05288-11] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Acquisition of immunity to Plasmodium falciparum sexual stages is a key determinant for reducing human-mosquito transmission by preventing the fertilization and the development of the parasite in the mosquito midgut. Naturally acquired immunity against sexual stages may therefore form the basis for the development of transmission-blocking vaccines, but studies conducted to date offer little in the way of consistent findings. Here, we describe the acquisition of antigametocyte immune responses in malaria-exposed individuals in Burkina Faso. A total of 719 blood samples were collected in a series of three cross-sectional surveys at the start, peak, and end of the wet season. The seroprevalence of antibodies with specificity for the sexual stage antigens Pfs48/45 and Pfs230 was 2-fold lower (22 to 28%) than that for an asexual blood stage antigen glutamate-rich protein (GLURP) (65%) or for the preerythrocytic stage antigen circumsporozoite protein (CSP) (54%). The youngest children responded at frequencies similar to those for all four antigens but, in contrast with the immune responses to GLURP and CSP that increased with age independently of season and area of residence, there was no evidence for a clear age dependence of responses to Pfs48/45 and Pfs230. Anti-Pfs230 antibodies were most prevalent at the peak of the wet season (P < 0.001). Our findings suggest that naturally acquired immunity against Pfs48/45 and Pfs230 is a function of recent exposure rather than of cumulative exposure to gametocytes.
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13
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A plant-produced Pfs230 vaccine candidate blocks transmission of Plasmodium falciparum. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:1351-7. [PMID: 21715576 DOI: 10.1128/cvi.05105-11] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Plasmodium falciparum is transmitted to a new host after completing its sexual cycle within a mosquito. Developing vaccines against the parasite sexual stages is a critical component in the fight against malaria. We are targeting multiple proteins of P. falciparum which are found only on the surfaces of the sexual forms of the parasite and where antibodies against these proteins have been shown to block the progression of the parasite's life cycle in the mosquito and thus block transmission to the next human host. We have successfully produced a region of the Pfs230 antigen in our plant-based transient-expression system and evaluated this vaccine candidate in an animal model. This plant-produced protein, 230CMB, is expressed at approximately 800 mg/kg in fresh whole leaf tissue and is 100% soluble. Administration of 230CMB with >90% purity induces strong immune responses in rabbits with high titers of transmission-blocking antibodies, resulting in a greater than 99% reduction in oocyst counts in the presence of complement, as determined by a standard membrane feeding assay. Our data provide a clear perspective on the clinical development of a Pfs230-based transmission-blocking malaria vaccine.
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14
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Bousema T, Sutherland CJ, Churcher TS, Mulder B, Gouagna LC, Riley EM, Targett GA, Drakeley CJ. Human immune responses that reduce the transmission of Plasmodium falciparum in African populations. Int J Parasitol 2011; 41:293-300. [PMID: 20974145 PMCID: PMC3052432 DOI: 10.1016/j.ijpara.2010.09.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 12/04/2022]
Abstract
Malaria-infected individuals can develop antibodies which reduce the infectiousness of Plasmodium gametocytes to biting Anopheles mosquitoes. When ingested in a bloodmeal together with gametocytes, these antibodies reduce or prevent subsequent parasite maturation in the insect host. This transmission-blocking immunity is usually measured in human sera by testing its effect on the infectivity of gametocytes grown in vitro. Here we evaluate evidence of transmission-blocking immunity in eight studies conducted in three African countries. Plasmodium falciparum gametocytes isolated from each individual were fed to mosquitoes in both autologous plasma collected with the parasites, and permissive serum from non-exposed donors. Evidence of transmission reducing effects of autologous plasma was found in all countries. Experiments involving 116 Gambian children (aged 0.5-15 years) were combined to determine which factors were associated with transmission reducing immune responses. The chances of infecting at least one mosquito and the average proportion of infected mosquitoes were negatively associated with recent exposure to gametocytes and sampling late in the season. These results suggest that effective malaria transmission-reducing antibodies do not commonly circulate in African children, and that recent gametocyte carriage is required to initiate and/or boost such responses.
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Affiliation(s)
- Teun Bousema
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Colin J. Sutherland
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Thomas S. Churcher
- Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK
| | - Bert Mulder
- Microbiology Laboratory Twente, Enschede, The Netherlands
| | | | - Eleanor M. Riley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Geoffrey A.T. Targett
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris J. Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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15
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Bousema T, Roeffen W, Meijerink H, Mwerinde H, Mwakalinga S, van Gemert GJ, van de Vegte-Bolmer M, Mosha F, Targett G, Riley EM, Sauerwein R, Drakeley C. The dynamics of naturally acquired immune responses to Plasmodium falciparum sexual stage antigens Pfs230 & Pfs48/45 in a low endemic area in Tanzania. PLoS One 2010; 5:e14114. [PMID: 21124765 PMCID: PMC2993929 DOI: 10.1371/journal.pone.0014114] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 09/16/2010] [Indexed: 11/23/2022] Open
Abstract
Background Naturally acquired immune responses against sexual stages of P. falciparum can reduce the transmission of malaria from humans to mosquitoes. These antigens are candidate transmission-blocking vaccines but little is known about the acquisition of sexual stage immunity after exposure to gametocytes, or their longevity and functionality. We conducted a longitudinal study on functional sexual stage immune responses. Methodology/Principal Findings Parasitaemic individuals (n = 116) were recruited at a health centre in Lower Moshi, Tanzania. Patients presented with gametocytes (n = 16), developed circulating gametocytes by day 7 (n = 69) or between day 7 and 14 (n = 10) after treatment or did not develop gametocytes (n = 21). Serum samples were collected on the first day of gametocytaemia and 28 and 84 days post-enrolment (or d7, 28, 84 after enrolment from gametocyte-negative individuals). Antibody responses to sexual stage antigens Pfs230 and Pfs48/45 were detected in 20.7% (72/348) and 15.2% (53/348) of the samples, respectively, and were less prevalent than antibodies against asexual stage antigens MSP-119 (48.1%; 137/285) and AMA-1 (52.4%; 129/246)(p<0.001). The prevalence of anti-Pfs230 (p = 0.026) and anti-Pfs48/45 antibodies (p = 0.017) increased with longer duration of gametocyte exposure and had an estimated half-life of approximately 3 months. Membrane feeding experiments demonstrated a strong association between the prevalence and concentration of Pfs230 and Pfs48/45 antibodies and transmission reducing activity (TRA, p<0.01). Conclusions/Significance In a longitudinal study, anti-Pfs230 and Pf48/45 antibodies developed rapidly after exposure to gametocytes and were strongly associated with transmission-reducing activity. Our data indicate that the extent of antigen exposure is important in eliciting functional transmission-reducing immune responses.
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Affiliation(s)
- Teun Bousema
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Joint Malaria Programme, Moshi, Tanzania
| | - Will Roeffen
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Hinta Meijerink
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Harry Mwerinde
- TPC District Designated Hospital, Tanzania Plantation Company, Lower Moshi, Tanzania
| | - Steve Mwakalinga
- Joint Malaria Programme, Moshi, Tanzania
- Department of International Health, Immunology, and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Marga van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Frank Mosha
- Joint Malaria Programme, Moshi, Tanzania
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
| | - Geoffrey Targett
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Eleanor M. Riley
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Chris Drakeley
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Joint Malaria Programme, Moshi, Tanzania
- * E-mail:
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16
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Targett GA, Greenwood BM. Malaria vaccines and their potential role in the elimination of malaria. Malar J 2008; 7 Suppl 1:S10. [PMID: 19091034 PMCID: PMC2604874 DOI: 10.1186/1475-2875-7-s1-s10] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on malaria vaccines is currently directed primarily towards the development of vaccines that prevent clinical malaria. Malaria elimination, now being considered seriously in some epidemiological situations, requires a different vaccine strategy, since success will depend on killing all parasites in the community in order to stop transmission completely. The feature of the life-cycles of human malarias that presents the greatest challenge to an elimination programme is the persistence of parasites as asymptomatic infections. These are an important source from which transmission to mosquitoes can occur. Consequently, an elimination strategy requires a community-based approach covering all individuals and not just those who are susceptible to clinical malaria. The progress that has been made in development of candidate malaria vaccines is reviewed. It is unlikely that many of these will have the efficacy required for complete elimination of parasites, though they may have an important role to play as part of future integrated control programmes. Vaccines for elimination must have a high level of efficacy in order to stop transmission to mosquitoes. This might be achieved with some pre-erythrocytic stage candidate vaccines or by targeting the sexual stages directly with transmission-blocking vaccines. An expanded malaria vaccine programme with such objectives is now a priority.
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Affiliation(s)
- Geoffrey A Targett
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
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17
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Murhandarwati E, Black C, Wang L, Weisman S, Koning‐Ward T, Baird J, Tjitra E, Richie T, Crabb B, Coppel R. Acquisition of Invasion‐Inhibitory Antibodies Specific for the 19‐kDa Fragment of Merozoite Surface Protein 1 in a Transmigrant Population Requires Multiple Infections. J Infect Dis 2008; 198:1212-8. [DOI: 10.1086/591943] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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18
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Bousema JT, Drakeley CJ, Kihonda J, Hendriks JCM, Akim NIJ, Roeffen W, Sauerwein RW. A longitudinal study of immune responses to Plasmodium falciparum sexual stage antigens in Tanzanian adults. Parasite Immunol 2007; 29:309-17. [PMID: 17518949 DOI: 10.1111/j.1365-3024.2007.00948.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Next to children, adults form a substantial part of the infectious reservoir that is responsible for the spread of malaria. In this longitudinal study, we determined sexual stage immune responses to Plasmodium falciparum and infectiousness to mosquitoes in adults from an area with intense malaria transmission. A cohort of 43 Tanzanian adults was followed for 18 months. Parasitological data were collected monthly; serum once every three months. Antibody prevalences were determined for sexual stage antigens Pfs230 and Pfs48/45 and circumsporozoite protein (NANP5)(n = 199). Functional transmission reducing activity (TRA) was assessed by standard membrane feeding assay (SMFA; n = 85). Cumulative parasite prevalence was 67.4% (29/43) for asexual stages and 34.9% (15/43) for gametocytes. Enrolment antibody prevalence was 95.3% (41/43) for NANP5, 18.9% (7/37) for Pfs230 and 7% (3/43) for Pfs48/45 epitope 3. TRA > 50% reduction was seen in 48.2% (41/85) and TRA > 90% reduction in 4.7% (4/85) of the samples. Our findings of low and inconsistent sexual stage immune responses are likely to be the result of a low exposure to gametocytes in this older age group. This may in turn be caused by effective asexual stage immunity. We conclude that the infectivity of older individuals is less likely to be affected by sexual stage immunity.
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Affiliation(s)
- J T Bousema
- Department of Medical Microbiology, University Medical Centre, Nijmegen, The Netherlands.
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19
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Drakeley CJ, Bousema JT, Akim NIJ, Teelen K, Roeffen W, Lensen AH, Bolmer M, Eling W, Sauerwein RW. Transmission-reducing immunity is inversely related to age in Plasmodium falciparum gametocyte carriers. Parasite Immunol 2006; 28:185-90. [PMID: 16629703 DOI: 10.1111/j.1365-3024.2005.00818.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Immunity to the sexual stages of Plasmodium falciparum is induced during natural infections and can significantly reduce the transmission of parasites to mosquitoes (transmission reducing activity; TRA) but little is known about how these responses develop with increasing age/exposure to malaria. Routinely TRA is measured in the standard membrane feeding assay (SMFA). Sera were collected from a total of 199 gametocyte carriers (median age 4 years, quartiles 2 and 9 years) near Ifakara, Tanzania; 128 samples were tested in the SMFA and generated TRA data classified as a reduction of > 50% and > 90% of transmission. TRA of > 50% was highest in young children (aged 1-2) with a significant decline with age (chi(2) trend = 5.79, P = 0.016) and in logistic regression was associated with prevalence of antibodies to both Pfs230 and Pfs48/45 (OR 4.03, P = 0.011 and OR 2.43 P = 0.059, respectively). A TRA of > 90% reduction in transmission was not age related but was associated with antibodies to Pfs48/45 (OR 2.36, P = 0.055). Our data confirm that antibodies are an important component of naturally induced TRA. However, whilst a similar but small proportion of individuals at all ages have TRA > 90%, the gradual deterioration of TRA > 50% with age suggests decreased antibody concentration or affinity. This may be due to decreased exposure to gametocytes, probably as a result of increased asexual and/or gametocyte specific immunity.
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Affiliation(s)
- C J Drakeley
- Ifakara Health Research and Development Centre, Ifakara, Tanzania.
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20
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Abstract
It is widely perceived that immunity to malaria is, to an extent, defective and that one component of this defective immune response is the inability to induce or maintain long-term memory responses. If true, this is likely to pose problems for development of an effective vaccine against malaria. In this article, we critically review and challenge this interpretation of the epidemiological and experimental evidence. While evasion and modulation of host immune responses clearly occurs and naturally acquired immunity is far from optimal, mechanisms to control blood-stage parasites are acquired and maintained by individuals living in endemic areas, allowing parasite density to be kept below the threshold for induction of acute disease. Furthermore, protective immunity to severe pathology is achieved relatively rapidly and is maintained in the absence of boosting by re-infection. Nevertheless, there are significant challenges to overcome. The need for multiple infections to acquire immunity means that young children remain at risk of infection for far too long. Persistent or frequent exposure to antigen seems to be required to maintain anti-parasite immunity (premunition). Lastly, pre-erythrocytic and sexual stages of the life cycle are poorly immunogenic, and there is little evidence of effective pre-erythrocytic or transmission-blocking immunity at the population level. While these problems might theoretically be due to defective immunological memory, we suggest alternative explanations. Moreover, we question the extent to which these problems are malaria-specific rather than generic (i.e. result from inherent limitations of the vertebrate immune system).
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Affiliation(s)
- Siske S Struik
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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21
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Drakeley CJ, Eling W, Teelen K, Bousema JT, Sauerwein R, Greenwood BM, Targett GAT. Parasite infectivity and immunity to Plasmodium falciparum gametocytes in Gambian children. Parasite Immunol 2004; 26:159-65. [PMID: 15367293 DOI: 10.1111/j.0141-9838.2004.00696.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immunity to the sexual stages of Plasmodium falciparum can be induced during natural infections. Characterization of this immunity may facilitate the design of a transmission-blocking vaccine (TBV). This study aimed to assess the prevalence and serological correlates of functional transmission-blocking immunity in Gambian children (aged 1-4 years old) who were P. falciparum gametocyte carriers. Serological assays showed 100% response to fixed, whole parasites but only 42% to live gametes. Responses to the antigens Pfs230 and Pfs48/45 were 54.1% and 37.3%, respectively, in an IgG1 ELISA. 14/55 sera were capable of reducing the infectivity of laboratory isolate NF54 in a standard membrane-feeding assay (SMFA). This activity was strongly correlated with IgG1 responses to Pfs48/45 (r = 0.49, P < 0.001) and to a serological reaction with epitopes of the same molecule (r = 0.38, P = 0.003). A weaker correlation was observed with IgG1 to Pfs230 (r = 0.29, P = 0.03). In direct membrane feeding assays (DMFA) with autologous isolates, sera from 4/29 children showed transmission-blocking activity. There was no correlation with serological assays and the DMFA or between the SMFA and DMFA. This may be caused by variation in sexual stage antigens and/or alternative modes of transmission-blocking immunity, both of which have implications for vaccine implementation.
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Affiliation(s)
- C J Drakeley
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel St., London WC1E 7HT, UK.
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22
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Gouagna LC, Ferguson HM, Okech BA, Killeen GF, Kabiru EW, Beier JC, Githure JI, Yan G. Plasmodium falciparummalaria disease manifestations in humans and transmission toAnopheles gambiae: a field study in Western Kenya. Parasitology 2004; 128:235-43. [PMID: 15074873 DOI: 10.1017/s003118200300444x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Transmission of the malaria parasitePlasmodiumis influenced by many different host, vector and parasite factors. Here we conducted a field study at Mbita, an area of endemic malaria in Western Kenya, to test whether parasite transmission to mosquitoes is influenced by the severity of malaria infection in its human host at the time when gametocytes, the transmission forms, are present in the peripheral blood. We examined the infectivity of 81Plasmodium falciparumgametocyte carriers to mosquitoes. Of these, 21 were patients with fever and other malaria-related symptoms, and 60 were recruited among apparently healthy volunteers. Laboratory-rearedAnopheles gambiaes.s. (local strain) were experimentally infected with blood from these gametocyte carriers by membrane-feeding. The severity of the clinical symptoms was greater in febrile patients. These symptomatic patients had higher asexual parasitaemia and lower gametocyte densities (P=0·05) than healthy volunteers. Ookinete development occurred in only 6 out of the 21 symptomatic patients, of which only 33·3% successfully yielded oocysts. The oocyst prevalence was only 0·6% in the 546 mosquitoes that were fed on blood from this symptomatic group, with mean oocyst intensity of 0·2 (range 0–2) oocysts per mosquito. In contrast, a higher proportion (76·7%) of healthy gametocyte carriers yielded ookinetes, generating an oocyst rate of 12% in the 1332 mosquitoes that fed on them (mean intensity of 6·3, range: 1–105 oocysts per mosquito). Statistical analysis indicated that the increased infectivity of asymptomatic gametocyte carriers was not simply due to their greater gametocyte abundance, but also to the higher level of infectivity of their gametocytes, possibly due to lower parasite mortality within mosquitoes fed on blood from healthy hosts. These results suggest that blood factors and/or conditions correlated with illness reduceP. falciparumgametocyte infectivity.
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Affiliation(s)
- L C Gouagna
- Human Health Division, Mbita Point Research and Training Station, International Centre of Insect Physiology an2d Ecology, P.O. Box 30772, Nairobi, Kenya.
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23
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Affiliation(s)
- Kim C Williamson
- Department of Biology, Loyola University Chicago, Chicago, Illinois 60626, USA.
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24
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Milek RL, Stunnenberg HG, Konings RN. Assembly and expression of a synthetic gene encoding the antigen Pfs48/45 of the human malaria parasite Plasmodium falciparum in yeast. Vaccine 2000; 18:1402-11. [PMID: 10618538 DOI: 10.1016/s0264-410x(99)00392-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pfs48/45 is an important transmission-blocking vaccine candidate antigen of the human malaria parasite Plasmodium falciparum. This study was aimed at synthesis of recombinant Pfs48/45 containing conformation-constrained epitopes of the native antigen in yeast. Since in the yeast Saccharomyces cerevisiae induction of gene-expression led to prematurely terminated transcripts, an entirely synthetic gene of higher GC content was assembled. Replacement of the AT rich natural gene by the synthetic gene relieved the observed premature transcription termination. Nevertheless, recombinant protein expression could not be detected. In contrast, in the yeast Pichia pastoris low levels of recombinant Pfs48/45 were produced upon induction of synthetic gene expression. The recombinant protein was shown to be disulphide-bridge constrained, but was not recognised by transmission-blocking antibodies and did not induce transmission-blocking sera in mice.
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Affiliation(s)
- R L Milek
- Department of Molecular Biology and Cell Biology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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25
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Milek RL, DeVries AA, Roeffen WF, Stunnenberg H, Rottier PJ, Konings RN. Plasmodium falciparum: heterologous synthesis of the transmission-blocking vaccine candidate Pfs48/45 in recombinant vaccinia virus-infected cells. Exp Parasitol 1998; 90:165-74. [PMID: 9769246 DOI: 10.1006/expr.1998.4315] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With the aim of developing transmission-blocking vaccines based on the sexual stage-specific surface antigen Pfs48/45 of the human malaria parasite Plasmodium falciparum, the gene encoding Pfs48/45 was incorporated into the genome of a recombinant vaccinia virus. In virus-infected mammalian tissue culture cells, recombinant Pfs48/45 antigen (rPfs48/45) is posttranslational modified to produce a highly N-glycosylated polypeptide. The rPfs48/45 protein was radiolabeled with ethanolamine, consisting of a further posttranslational modification in the form of a glycosylphosphatidylinositol anchor at its carboxy-terminal end. The rPfs48/45 was not detected on the surface of the infected cells; instead, it remained within the secretion pathway of mammalian cells irrespective of the duration of infection or culture temperature. Studies with monoclonal antibodies specific for disulfide band-dependent epitopes of Pfs48/45 revealed that recombinant Pfs48/45 is not folded in its authentic conformation even if N-glycosylation was chemically inhibited. Infection of mice and rabbits with recombinant virus elicited Pfs48/45-specific antibodies; however, the antisera failed to block parasite transmission in a standard mosquito membrane-feeding assay.
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MESH Headings
- Animals
- Antigens, Protozoan/biosynthesis
- Antigens, Protozoan/immunology
- Antigens, Protozoan/metabolism
- Antigens, Surface/biosynthesis
- Antigens, Surface/immunology
- Antigens, Surface/metabolism
- Cell Line
- Fluorescent Antibody Technique, Indirect
- Malaria Vaccines/biosynthesis
- Malaria Vaccines/metabolism
- Malaria, Falciparum/prevention & control
- Mice
- Mice, Inbred BALB C
- Plasmodium falciparum/immunology
- Precipitin Tests
- Protein Processing, Post-Translational
- Protozoan Proteins/biosynthesis
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Rabbits
- Vaccines, Synthetic/biosynthesis
- Vaccines, Synthetic/metabolism
- Vaccinia virus/physiology
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Affiliation(s)
- R L Milek
- Department of Molecular Biology, University of Nijmegen, Toernooiveld 1, Nijmegen, 6525 ED, The Netherlands
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Milek RL, Roeffen WF, Kocken CH, Jansen J, Kaan AM, Eling WM, Sauerwein RW, Konings RN. Immunological properties of recombinant proteins of the transmission blocking vaccine candidate, Pfs48/45, of the human malaria parasite Plasmodium falciparum produced in Escherichia coli. Parasite Immunol 1998; 20:377-85. [PMID: 9767603 DOI: 10.1046/j.1365-3024.1998.00171.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A precondition for the development of a transmission blocking vaccine based on the sexual stage-specific surface antigen Pfs48/45 of Plasmodium falciparum is its heterologous synthesis in a native state. Here we describe the production of recombinant Pfs48/45 in Escherichia coli. Two recombinant proteins, of which one is a glutathione-S-transferase fusion protein, were produced. Enzyme-linked immunosorbent assays showed that at least a subfraction of the recombinant proteins had a conformation capable of binding transmission blocking monoclonal antibodies. However, despite the fact that both proteins were very immunogenic, they did not induce transmission blocking immunity in mice or rabbits. Immunological studies with congenic mouse strains demonstrated that immune responses could be boosted with gametocyte extracts and were not restricted to a particular class II major histocompatibility complex haplotype.
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Affiliation(s)
- R L Milek
- Department of Molecular Biology and Cell Biology, University of Nijmegen, Toernooiveld 2, 6525 ED Nijmegen, The Netherlands
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Lensen AH, Bolmer-Van de Vegte M, van Gemert GJ, Eling WM, Sauerwein RW. Leukocytes in a Plasmodium falciparum-infected blood meal reduce transmission of malaria to Anopheles mosquitoes. Infect Immun 1997; 65:3834-7. [PMID: 9284160 PMCID: PMC175547 DOI: 10.1128/iai.65.9.3834-3837.1997] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Mosquitoes are infected with Plasmodium falciparum by taking a blood meal from a gametocyte carrier. Since a mosquito takes a volume of 1 to 2 microl, a blood meal may contain 1 x 10(4) to 3 x 10(4) leukocytes (WBC). The majority of WBC are composed of neutrophils which may phagocytose and kill developing gametes inside the mosquito midgut. Phagocytosis was measured in vitro by a luminol-dependent chemiluminescence (CL) assay. In the presence of P. falciparum gametes, sera from areas of endemicity had an increased CL response compared to controls. In mosquito membrane feeding experiments some such sera showed a transmission reduction which was related to the presence of viable WBC. The results of this study suggest that phagocytosis of opsonized gametes inside the mosquito midgut occurs and can contribute to a reduction in the transmission of P. falciparum parasites.
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Affiliation(s)
- A H Lensen
- Department of Medical Microbiology, University Hospital Nijmegen, University of Nijmegen, The Netherlands
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Drakeley CJ, Duraisingh MT, Póvoa M, Conway DJ, Targett GA, Baker DA. Geographical distribution of a variant epitope of Pfs48/45, a Plasmodium falciparum transmission-blocking vaccine candidate. Mol Biochem Parasitol 1996; 81:253-7. [PMID: 8898341 DOI: 10.1016/0166-6851(96)02718-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- C J Drakeley
- Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, UK
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Sinden RE, Butcher GA, Billker O, Fleck SL. Regulation of infectivity of Plasmodium to the mosquito vector. ADVANCES IN PARASITOLOGY 1996; 38:53-117. [PMID: 8701799 DOI: 10.1016/s0065-308x(08)60033-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- R E Sinden
- Department of Biology, Imperial College of Science, Technology and Medicine, South Kensington, London, UK
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30
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Malaria Transmission-Blocking Immunity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995. [DOI: 10.1007/978-1-4615-1891-4_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Simonetti AB, Billingsley PF, Winger LA, Sinden RE. Kinetics of expression of two major Plasmodium berghei antigens in the mosquito vector, Anopheles stephensi. J Eukaryot Microbiol 1993; 40:569-76. [PMID: 8401470 DOI: 10.1111/j.1550-7408.1993.tb06109.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Expression of a 21 kDa determinant (Pbs21), first detected on the surface of ookinetes, and of the circumsporozoite protein (CSP) was studied by immunofluorescence and Western blots during the developmental cycle of Plasmodium berghei in the mosquito Anopheles stephensi. The expression of Pbs21 was predominantly localised on the ookinete surface one day after the infectious blood meal, and thereafter reactivity declined to a minimum on days 2 and 3, the time of onset of oocyst development. A gradual increase in fluorescence was observed on the oocysts from day 6 that was retained until day 17 post-infection. In contrast, sporozoites released from oocysts or salivary glands showed little or no antibody labelling with anti-Pbs21. Circumsporozoite protein was not detectable in any midgut preparations until 5-6 days after feeding, when reactivity was observed against immature oocysts. Expression then continued and increased throughout oocyst and sporozoite development. Western blots confirmed that Pbs21 was expressed minimally during the oocyst development but was not detectable in sporozoites. Co-localisation of anti-Pbs21 and anti-CSP monoclonal antibodies to the 50 kDa and 60 kDa bands in Western blots of sporozoite suggests immunological cross-reactivity between the CSP and the anti-21 kDa antibodies.
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Affiliation(s)
- A B Simonetti
- Department of Biology, Imperial College of Science, Technology and Medicine, London, United Kingdom
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Kocken CH, Jansen J, Kaan AM, Beckers PJ, Ponnudurai T, Kaslow DC, Konings RN, Schoenmakers JG. Cloning and expression of the gene coding for the transmission blocking target antigen Pfs48/45 of Plasmodium falciparum. Mol Biochem Parasitol 1993; 61:59-68. [PMID: 8259133 DOI: 10.1016/0166-6851(93)90158-t] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The gene encoding the gametocyte/gamete-specific membrane protein Pfs48/45 of Plasmodium falciparum has been cloned. The Pfs48/45 gene is a non-interrupted, single copy gene that codes for a hydrophobic, non-repetitive protein of 448 amino acid residues containing a putative signal peptide at the N-terminus, a hydrophobic C-terminus and 7 potential N-glycosylation sites. Antibodies directed against a Pfs48/45-glutathione-S-transferase fusion protein reacted with both the 45-kDa and 48-kDa proteins of gametocytes. When Pfs48/45 is expressed in the baculovirus-insect cell system the recombinant Pfs48/45 protein is targeted and exposed to the insect cell surface in such a configuration that it is recognized by transmission-blocking anti-45/48-kDa monoclonal antibodies.
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Affiliation(s)
- C H Kocken
- Department of Molecular Biology, Faculty of Science, Nijmegen, The Netherlands
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Abstract
Antibodies to sexual stage malaria parasites block transmission of Plasmodium by female mosquitoes. With the recent isolation of genes encoding several of the target antigens of transmission-blocking antibodies, the development of a subunit transmission-blocking vaccine against malaria is now a realistic goal.
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Affiliation(s)
- D C Kaslow
- Laboratory of Malaria Research, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Wizel B, Kumar N. Identification of a continuous and cross-reacting epitope for Plasmodium falciparum transmission-blocking immunity. Proc Natl Acad Sci U S A 1991; 88:9533-7. [PMID: 1719534 PMCID: PMC52752 DOI: 10.1073/pnas.88.21.9533] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Identification of continuous epitopes in the target antigens of Plasmodium falciparum transmission-blocking antibodies is likely to facilitate the production of a subunit peptide vaccine. Two such epitopes shared among several sexual-stage antigens were identified with murine monoclonal antibodies. An epitope recognized by four monoclonal antibodies capable of blocking infectivity of gametocytes in the mosquitoes is shared among three antigens (230, 48/45 doublet, and 27 kDa). These antigens are synthesized at different times during the development and maturation of gametocytes, and the blocking epitope appears conserved among parasites from diverse geographical locations. Immune response against such a unique epitope (continuous, cross-reacting, and conserved) is likely to be boosted by natural infection. The 27-kDa protein is reported here as a target of malaria transmission-blocking monoclonal antibodies, and the cross-reacting epitope represents an attractive candidate for a transmission-blocking vaccine.
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Affiliation(s)
- B Wizel
- Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205
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Graves PM, Doubrovsky A, Beckers P. Antibody responses to Plasmodium falciparum gametocyte antigens during and after malaria attacks in schoolchildren from Madang, Papua New Guinea. Parasite Immunol 1991; 13:291-9. [PMID: 1712931 DOI: 10.1111/j.1365-3024.1991.tb00283.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Sera from 49 school children in Madang, Papua New Guinea with malaria and follow-up sera from 40 of these cases were tested by competitive ELISA for antibodies capable of inhibiting binding of eight monoclonal antibodies (MoAbs) to Plasmodium falciparum gametocytes. The proportion of sera inhibiting each MoAb ranged from 31.2% to 85.7%. At follow-up, the proportion of inhibitory sera decreased for 3 MoAbs, did not change significantly for 4 MoAbs and increased for one MoAb. When sera were grouped according to whether the follow-up blood slide was positive or negative, further trends emerged for MoAbs against the gamete surface antigen Pfs 48/45. Antibody levels to the IA3-B8 epitope decreased in follow-up positive cases, but remained unchanged for follow-up negative cases. The converse was observed for the IIC5-B10 epitope with an increase of antibody in follow-up positive cases and no change in the negative cases. Amount of antibody to the 3G12/58 epitope decreased when the follow-up was negative but not when it was positive. Increase in antibody to the 3E12/58 epitope occurred at the follow-up sample irrespective of the blood slide result. Thus four distinct patterns of longitudinal antibody response were observed against four epitopes on the same molecule.
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Affiliation(s)
- P M Graves
- Queensland Institute of Medical Research, Herston, Brisbane
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Abstract
Owing to the demonstration that the immune response of inbred mice to some defined malaria antigens is influenced by the major histocompatibility complex (MHC), and the finding that only a minority of individuals living in malaria-endemic areas appear to recognize such antigens, there are fears that synthetic subunit malaria vaccines will be poorly immunogenic in a substantial proportion of the target population. Such fears have been reinforced by the results of the first two human malaria vaccine trials. In this review Eleanor Riley, Olle Olerup and Marita Troye-Blomberg summarize the experimental evidence for MHC-related genetic restriction of malaria immunity and discuss some alternative explanations for nonresponsiveness in populations living in malaria-endemic areas.
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Affiliation(s)
- E M Riley
- Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN, UK
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